Why would the dealership or even GM give a dern about a customer trying to keep his engine to last longer. Do some reasearch and look at what an engine looks like on the inside that has used Lucas Oil treatment. I have seen it on super high mileage engines and its astonishing how clean and golden looking they are. It reminds of the old days when everyone used slick-50.
I'm not debating whether the Lucas treatment works or not.... I have used some Lucas products with miraculous results. I just don't believe it should be the go-to on a modern engine from the get-go.... and don't get me started on why dealership or GM would give a darn about the customer doing the right thing to make the engine last longer ? That is a big gray area.... unless I see an official document from GM that says it is ok to use Lucas oil stabilizer I would not trust that they will stand behind it.
Prior to this recall, if anyone used 0W-40 on their 6.2L engine because they thought it would make their engine last longer, I'm sure your dealership or GM wouldn't have honored any warranty claims. Now there is official documentation from GM showing the 0W-40 offers an "enhanced further level of protection" so its OK now....
With all due respect, I'm not going to take your guarantee.. yes you are technically correct that Lucas oil treatment is more than likely good, but it is not officially OK per GM so its a big gray area... Having said all this.. I wouldn't be opposed to using it if your dealership is the one that sold that treatment and poured it in as part of the oil service. If anything happens, you can be blamed.